This invention relates to chain brackets, and especially to trolley brackets for supporting conveyor chain links in overhead conveyor systems. More particularly, the invention is an improved bracket or trolley bracket which is more economical to manufacture because it is stamped from sheet metal and has increased chain support strength, as well as to a method for making such brackets.
Trolley and other chain brackets used in overhead conveyor systems are typically subjected to many stresses and strains. In the typical manufacturing plant utilizing an overhead conveyor, the conveyor includes numerous horizontal corners as well as changes in vertical height along its length. Each trolley bracket, which is typically supported by a wheel assembly on an overhead I-beam-type or other type conveyor rail or the like, is joined to a conveyor chain which extends along the conveyor rail by means of one of the chain links. A typical method is to insert a pair of trolley brackets through the open center of the link in back-to-back fashion and thereafter move the brackets outwardly with a spacer and secure them with bolts or the like to hold the link in place on the brackets. Other chain brackets, such as those typically fitted between trolley brackets, are also secured to the chain in a similar fashion.
When each combination of brackets and a chain link encounters turns in the conveyor and especially vertical changes in height, the chain changes direction urging the bracket connected links through that same change in direction. This tends to cause the rigidly mounted links to "rock" on the brackets resulting in wear to or deformation of the chain and brackets.
One prior known type of trolley bracket was forged from steel or another metal. The forging method is "tremendously more expensive because it is labor intensive and requires numerous forging dies. Such dies tend to wear out quickly because of extensive configurations and projections in the trolley bracket to be formed. A forged bracket also includes metal which has to be softened by heating to allow forging, is heavier than a stamped sheet metal bracket, is more expensive to heat treat for hardness after forging, and requires secondary machining before use.
Other prior trolley brackets were stamped from sheet metal. Some of these brackets included chain support surfaces which were bent out of the sheet metal itself. Such chain supports often bent and were deformed when stressed during use on a conveyor and subjected to the above "rocking" link motion. In addition, some of the prior stamped trolley brackets supported the chain only with sheared edges of the stamped metal itself which increased wear on the chain.
Accordingly, a need was evident for an economical chain bracket, especially a trolley bracket for overhead conveyor systems which would be stronger and more durable in use, could be more easily and economically heat treated for hardness after formation, and which would include stronger chain supports which would remain in their proper position and resist wear even under stress and load during use.
This invention provides a solution to the above need and problems. Alternative but distinct solutions to the same problems and need are disclosed in copending, commonly assigned, U.S. Patent applications Ser. No. 872,245, now U.S. Pat. No. 4,210,238, invented by Charles C. Frost, Gerald W. Gurney and Frederick Sytsma and Ser. No. 872,265, invented by Gerald W. Gurney and Siegfried K. Weis, both of which were filed on even date herewith.